Replacing the Sand Bed

[SaltyMix]

Hi all and thank you in advance,

My LFS guy and I have been dealing with a major phosphate spike in my tank that led to a hair algae bloom and a ton of problems. The problem is there was really nothing to cause it that we could find…until today.

Despite consistent water changes and purigen and everything else, my phosphates have been consistently 2.00ppm and between 0.00-1ppm in nitrates for about 2 months now.

Calcium is at 380
DKH is at 11
Salinity is at 2.5

My tank is a 30 gallon. Running a canister filter with purigen and carbon.

I additionally have almost too much clean up crew (30 snails, 12 blue legged hermits, 2 conch, 2 peppermint shrimp, 1 brittle star, 1 Luzon starfish, and 1 white pincushion sea urchin, 1 porcelain crab). I’m feeding 1/5 cube of frozen food 2 times daily and a small nori strip about 1 per week (switched from frozen marine cuisine suspecting that the krill was not being eaten by the tank to plain mysis shrimp). Nothing is dead (I checking for life in all livestock at least once a week), and clean the sand bed every water change. I have no macro algae. I do have some corals and want to add more.


My fish are as follows: 2 oscillaris clowns, 1 banggai cardinal, 1 fire fish, 1 mandarin dragonet, and 1 baby tomini tang (the tang is for algae control and will go back to the LFS once she’s grown a bit on agreement/recommendation with the shop), and one Indonesian anemone. All my fish have a good condition score, with none being too skinny or too fat and they’re all voracious eaters.

Today, with my water test my LFS guy finally asked me what my sand bed was and if it was argonite.

Surprise! It’s not! He said that’s definitely the problem and explains why I could never get my sea cucumber to go on the sand bed and finally just retuned it to the store because I knew it wasn’t going to make it in my tank.

From my pictures we couldn’t tell exactly what the sand is and I don’t remember the brand. I just know it was one of my first tank buys at a smaller fish shop. (Pic attached).

I had no idea that argonite is important. So he recommends I replace the sand bed since it’s probably leeching pollutants into the water and do a 50% water change. (All my corals and fish are healthy so whatever is leeching in isn’t doing damage yet).

The problem is the web warns that using caribsea live reef sand (argonite), which is what I took home to do this with, will upset the bacteria in my tank. I’m not sure that’s even a problem at this point since I’m having so many issues with phosphates and hair algae.

Can I replace the sand bed all at once with the live reef sand? I don’t want to risk the sand mixing and just have this problem continue.

Any thoughts on how to do this safely?

My LFS guy just said “switch the sand bed” and it’s utterly my fault for not getting a recommendation/instructions on exactly how to replace it and of course the LFS is closed for the weekend so he can go on vacation. I live in a rural area and my LFS is about 1 hours drive away.

I’m just so relieved that after everything this might be the answer.

Also, newbie reefers, don’t let your local mom and pop store that doesn’t have marine fish sell you any old aquarium sand…which is what happened to me. Apparently it’s got to be argonite.

 

[Subsea]

Substrate does not have to be aroggonite. I like using aroggonite because of its buffering properties.

Not quite sure that I understand the problem.

I don’t understand your parameters of salinity. Please explain.

Calcium is at 380
DKH is at 11
Salinity is at 2.5

 

[fish_collector]

I doubt your issues are related to the sand in your tank, but maybe I guess. Yes aragonite or crushed coral is typically what's used for marine tanks. I've always been told it was due the alk and pH buffering ability of it, but in my opinion we keep our marine tanks near 8 but aragonite should be inert at that pH. To realize any kind of buffer the pH would have to be down in the 6s, like in a calcium reactor, but that is well out of the scope of what the OP is looking for .

You will get a variety of responses regarding removing the sand bed of a marine tank all at once with the primary reason being the unwanted release of hydrogen sulfide trapped deep within the sand bed. I personally don't believe that to be the case because sand beds aren't usually deep enough or made up of fine enough grains to go anaerobic, which is what's required to form hydrogen sulfide gas. If your sand bed was 6" deep and made up of sugar sized grains then yes there could be issues. But let's say if it was 2" deep and made up of grains that were 1-2mm then you'll be fine to use a siphon hose to remove it. It siphons out rather quickly. I've removed several sand beds from my aquaria all at once and never once saw any bubbles that had formed from within and never had any bad reactions to doing so. But as I said you'll get some others who will say don't try it lol. I've done it and it was no big deal.

The Caribsea sand, Aragalive I think is what it's called, will be dirty if you put it into the tank without rinsing it a bunch of times in a bucket, but the caveat to that is you are going to kill off whatever kind of bacteria is in the sand by doing so, so you'll have to use salt water to rinse it. It has been debated that what is in the Caribsea Aragalive isn't super effective for nitrification anyways but it's still a good product to use, I used it my reef tank originally as well. It does need to be rinsed before use or else it'll cloud the tank water for several days, mine did.

Perhaps you can check to verify your source water is clean and as near 0 TDS as you can get it. Often times you can create odd problems by using source water that's not pure enough. High nutrient levels and nuisance algae in a tank that's less than 6 months old is common. There's almost too many things that could cause the issues you are having to list them all here. Swap out your sand if you want to, and just be patient with it. I've found it easier to make one change at a time and then leave the tank alone for a while to see if your change has the effect you were after.

This probably wasn't as helpful as you'd have liked, sorry.

 

[fish_collector]

Maybe the OPs salinity is 1.025?

 

[SaltyMix]

I doubt your issues are related to the sand in your tank, but maybe I guess. Yes aragonite or crushed coral is typically what's used for marine tanks. I've always been told it was due the alk and pH buffering ability of it, but in my opinion we keep our marine tanks near 8 but aragonite should be inert at that pH. To realize any kind of buffer the pH would have to be down in the 6s, like in a calcium reactor, but that is well out of the scope of what the OP is looking for .

You will get a variety of responses regarding removing the sand bed of a marine tank all at once with the primary reason being the unwanted release of hydrogen sulfide trapped deep within the sand bed. I personally don't believe that to be the case because sand beds aren't usually deep enough or made up of fine enough grains to go anaerobic, which is what's required to form hydrogen sulfide gas. If your sand bed was 6" deep and made up of sugar sized grains then yes there could be issues. But let's say if it was 2" deep and made up of grains that were 1-2mm then you'll be fine to use a siphon hose to remove it. It siphons out rather quickly. I've removed several sand beds from my aquaria all at once and never once saw any bubbles that had formed from within and never had any bad reactions to doing so. But as I said you'll get some others who will say don't try it lol. I've done it and it was no big deal.

The Caribsea sand, Aragalive I think is what it's called, will be dirty if you put it into the tank without rinsing it a bunch of times in a bucket, but the caveat to that is you are going to kill off whatever kind of bacteria is in the sand by doing so, so you'll have to use salt water to rinse it. It has been debated that what is in the Caribsea Aragalive isn't super effective for nitrification anyways but it's still a good product to use, I used it my reef tank originally as well. It does need to be rinsed before use or else it'll cloud the tank water for several days, mine did.

Perhaps you can check to verify your source water is clean and as near 0 TDS as you can get it. Often times you can create odd problems by using source water that's not pure enough. High nutrient levels and nuisance algae in a tank that's less than 6 months old is common. There's almost too many things that could cause the issues you are having to list them all here. Swap out your sand if you want to, and just be patient with it. I've found it easier to make one change at a time and then leave the tank alone for a while to see if your change has the effect you were after.

This probably wasn't as helpful as you'd have liked, sorry.

Thank you! This is super helpful! My tank is almost 2 years old so I still think it’s weird to have all these issues.

I think I’ll replace the sandbed and wait and see. My LFS guy’s concern is that the incorrect sand is sponging up phosphates then leeching them and possibly heavy metals back into the water.

 

[Privateye]

It kind of looks like aragonite to me. Are you sure it isn't?

Aragonite is a calcium carbonate crystal, but other calcium carbonate products can be used too. Crushed coral is one you hear about often. I've even used the calcium carbonate they sell for chickens (as gizzard stones) in tanks before. Perhaps what you have was just a different term? It doesn't look like the white aquarium gravel sold for freshwater tanks (which are painted).

Here's the other thing: calcium carbonate (e.g. aragonite and live rock) is what soaks up the phosphate. If you had silica sand (like you find at most beaches) it wouldn't bind the phosphate. So the idea that your substrate is absorbing phosphate is kind of dependent on it being aragonite. It's actually the correct sand that absorbs the phosphate.

That's neither here nor there though. If your substrate is packed with phosphate, then replacing it sounds good.

 

[exnisstech]

I don't really see a lot of algae in the tank and the sand looks good to me.
Maybe just remove the sand bed even tho I doubt it's your problem. I run 3 bare bottom tanks and one with sand. You could always add sand back later after you see if removing it corrects your issues.
I'm not a believer that high PO4 is a driver of gha. How high is your PO4? Every tank I've had a GHA problem has been tanks with low N and P not high.
My only basis for believing high PO4 is not a driver of nuisance algae is my personal experience so it's anecdotal with no science to back it.
One if my near zero N and P tanks.

And another. pic was taking during a manual cleaning.

The opposite

This tank ran with PO4 0.4 - 0.6 for 6 years. Bare bottom except for a little on the left end where I had clams

This one is has been running for 3 years years and PO4 has never been below 0.4 and that's after running GFO to bring it down from a flashing 0.9 on my Hanna ULR tester. I have no ideas how high it actually gets because i can't test higher than 0.9.
Two halves of the tank to show how clean the rock is. Tank is too long for me to get a detailed FTS This one also bare bottom.

Do you have a CUC?
I also think having coral compete for nutrients can help keep algae at bay. But as mentioned I have no proof, just my limited experience to go by.

 

[EnterName]

Thank you! This is super helpful! My tank is almost 2 years old so I still think it’s weird to have all these issues.

I think I’ll replace the sandbed and wait and see. My LFS guy’s concern is that the incorrect sand is sponging up phosphates then leeching them and possibly heavy metals back into the water.

Like Privateye said all calcium carbonate will buffer phosphates, so aragonite will do so as well. This means if you perform a 25% water change phosphate won't drop by 25% because precipitates phosphates will just redissolve from rockscape and substrate. That's why generally phosphate adsorbers are used for a more efficient removal.

If you really want to remove the substrate I would take it out in small batches so you don't stir up too much detritus at once. After having removed everything I would try to get phosphates to the desired level in your tank and add new sand in small batches because it might now act the opposite way by adsorbing phosphate. I switched tanks and am still in the process of replacing the substrate as I'm running very low nutrients and would bottom out when adding too much sand at once. Note that even aragonite will release some silicate impurities and you will probably have to deal with brown diatom stains for quite a while when doing this. They will be limited to the substrate and won't hurt your corals though.

 

[SaltyMix]

Substrate does not have to be aroggonite. I like using aroggonite because of its buffering properties.

Not quite sure that I understand the problem.

I don’t understand your parameters of salinity. Please explain.

Calcium is at 380
DKH is at 11
Salinity is at 2.5

I’m so sorry, excuse me and my math related learning disorder. Numbers are difficult and I was panicking. My salinity is 1.026.